The present invention relates to a programmable control mechanism for defining the rules of operation of a mobile communications unit.
Prepaid cellular service is a form of cellular service in which a user must pay in advance for use of the service. Typically, a user purchases a definite amount of air time wireless network access (airtime) at an initially pre-defined exchange of monetary value versus units of airtime credit from a prepaid cellular service provider. These measures of units of airtimes are commonly valued at units of minutes. When the user places or receives a call or otherwise uses the service, the service provider decrements the user's pre-purchased air time units. The rate at which pre-purchased air time unit is deducted per unit of time is known as the deduct rate. Once the pre-purchased air time unit has been exhausted, the user is denied service until the user purchases additional units.
The deduct rate applied against a user's pre-purchased air time unit varies according to call type. Examples of different call types include local calls, local long distance calls, international long distance calls, free calls, and roaming and data calls; all of which may be inbound or outbound. The call type can be determined by referencing a set of rules, such as the telephone numbering plan, which define the length and format of telephone numbers within a telephone system.
However, telephone numbering plans vary significantly from country to country and in many cases differ from region to region within the same country. For example, in the United States, a seven to ten digit telephone number may correspond to a local call. An eleven digit telephone number (one+area code+seven digits) may be long distance, local or free call, depending on the area code. In Peru, however, a local number is defined as a sequence of six digits, except in the city of Lima where a local number is seven digits long. In Mexico, a local telephone number is eight digits long in some areas, and seven digits long in others. In Brazil, by contrast, all local numbers are always eight digits long.
Additionally, rules for determining toll free and emergency calls vary significantly from country to country. In the United States, “911”, “*911” and “#911” are an emergency number and are toll free. Similarly, calls placed to “800” exchanges are generally toll free. However, this is not the case in Mexico or Costa Rica. Every country has reserved a different set of emergency and toll free numbers.
To program prepaid cellular telephones with software capable of resolving every conceivable international variation in telephone numbering and tariff rules would consume an unacceptable level of a telephone's limited memory and processing power. To avoid this problem, prepaid cellular telephones employ customized algorithms loaded into the firmware to compute deduct rates. The customized software is limited to processing rules from one country or one specific region. To be able to use the prepaid telephone in a different region, the user must either buy a telephone customized to operate in that region, or must have the telephone reprogrammed with the appropriate customized software.
However, employing customized region-specific algorithms in prepaid cellular telephones is undesirable for the frequent traveler. Moreover, the process of “re-flashing” the firmware of a prepaid telephone with customized software to process the rule set of a different country or region generally requires transporting the telephone to a service location for reprogramming. This results in added cost and inconvenience to both users and prepaid cellular providers.
Thus, there exists a need in the art for a method and system of flexibly and conveniently enabling prepaid cellular telephones to compute appropriate unit deduction rates in the broadest possible variety of international or rate changing national environments.